linux-kernel - Re: [PATCH] perf: Handle DT_UNKNOWN on filesystems that don't support d

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20101121155252.GA2527@BohrerMBP>
Date:	Sun, 21 Nov 2010 09:52:52 -0600
From:	Shawn Bohrer <sbohrer@...advisors.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf: Handle DT_UNKNOWN on filesystems that don't
 support d_type

On Sat, Nov 20, 2010 at 10:48:36PM -0200, Arnaldo Carvalho de Melo wrote:
> Em Sat, Nov 20, 2010 at 06:42:19PM -0600, Shawn Bohrer escreveu:
> > Some filesystems like xfs and reiserfs will return DT_UNKNOWN for the
> > d_type.  Handle this case by calling stat() to determine the type.
> 
> Thanks for the fix, just waiting for some more reviewers to chime in,
> seems odd, like readdir_r has a bug.

The readdir_r man page says the following:

       If  the  file type could not be determined, the value DT_UNKNOWN
       is returned in d_type.

       Currently, only some file  systems  (among  them:  Btrfs,  ext2,
       ext3,  and  ext4)  have  full support returning the file type in
       d_type.  All applications  must  properly  handle  a  return  of
       DT_UNKNOWN.

So it isn't a bug in readdir_r.  This also isn't the only place that
perf uses readdir/readdir_r, and doesn't handle DT_UNKNOWN. In the
other locations it looked to me like it was only reading from debugfs,
so I don't think it matters.

> Even if that is the case we'll have to cope, and doing the extra stat
> only when in "doubt" (i.e. when getting DT_UNKNOWN) seems the right
> thing to me.
> 
> - Arnaldo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/